Apparatus for insulating and electrically connecting piezoelectric motor in dual stage actuator suspension

ABSTRACT

Apparatus and method for selectively applying a voltage to one major surface of a pair of piezoelectric motors (PZTs) on a disk drive head suspension with a primary plane of a load beam of the head suspension parallel to the major surfaces of the PZT elements electrically insulated from the load beam. Electrical connections to the PZTs are made via wires, solder, conductive epoxy or electro-mechanical attachment of a plated surface of the PZT with a bond pad on an electrically isolated substrate. Lead extensions or separate pieces may be used to connect to the PZTs. The PZTs may be located on a major surface of the load beam, or may be assembled in a pre-fabricated motor assembly before being installed in the head suspension. Apertures in the load beam and other layers permit physical installation of the PZT motors and enable electrical connection to the PZTs.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/416,479 filed Oct. 7, 2002, the entire contents of which are herebyexpressly incorporated by reference.

FIELD OF THE INVENTION

This invention is directed to differential actuation of one or morepiezoelectric transducer (PZT) motors on a disk drive head suspension.

BACKGROUND OF THE INVENTION

Conventionally, PZT motors have a generally planar configuration, withone or two opposing major faces plated or otherwise coated with aconductive material, such as gold. Conventionally, it has been known toground one face of the PZT and electrically energize the other face toactuate the PZT. Applying one polarity of voltage causes the PZT tocontract in a direction parallel to the faces having electrodes, whileapplying the other polarity causes the PZT to expand in a directionparallel to the plane of the opposing major faces having the electrodes.It is to be understood that, while the PZT is expanding in the directionparallel to the plane of the opposing major faces, it is correspondinglycontracting in a perpendicular direction, and conversely, when the PZTis contracting in the direction parallel to the plane of the opposingmajor faces, it is correspondingly expanding in the perpendiculardirection. The present invention preferably makes use of the movement(of expansion or contraction) in the direction parallel to the plane ofthe opposing major faces carrying electrodes, while accommodating or“tolerating” the movement perpendicular thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of the suspension assembly showing a pair ofPZT motors.

FIG. 2 is a bottom plan view of the suspension assembly of FIG. 1.

FIG. 3 is an enlarged fragmentary view of the top of the suspensionassembly from FIG. 1, showing details of the PZT motors and the topelectrical connections thereto.

FIG. 4 is an enlarged fragmentary plan view of the bottom of thesuspension assembly of FIG. 1.

FIG. 5 is a section view along line A—A of FIG. 3.

FIG. 6 is an exploded view of the suspension assembly of FIG. 1.

FIG. 7 is a perspective view of suspension assembly of FIG. 1 from afirst side.

FIG. 8 is a perspective view of the suspension assembly of FIG. 1 from asecond side opposite the first side shown in FIG. 7.

FIG. 9 is a top plan view of a first version of a first alternativeembodiment wherein the PZT motors are ultrasonically bonded toextensions of the conductive leads formed from the flexure material.

FIG. 10 is a bottom plan view of the version shown in FIG. 9.

FIG. 11 is a composite view of FIGS. 9 and 10 with hidden lines shownfor clarity.

FIG. 12 is a section view along line I—I of FIG. 11.

FIG. 13 is a section view along line II—II of FIG. 11.

FIG. 14 is a top plan view of a second version of the first alternativeembodiment wherein ultrasonic bonding using a pair of extra pieceselectrically attach the PZT motors to the conductive leads formed fromthe flexure material.

FIG. 15 is a bottom plan view of the version shown in FIG. 14.

FIG. 16 is a composite view of FIGS. 14 and 15 with hidden lines shownfor clarity.

FIG. 17 is a section view along line I—I of FIG. 16.

FIG. 18 is a section view along line II—II of FIG. 16.

FIG. 19 is a top plan view of a third version of the first alternativeembodiment wherein the PZT motors are attached using solder orconductive epoxy to extensions of the conductive leads formed from theflexure material.

FIG. 20 is a bottom plan view of the version shown in FIG. 19.

FIG. 21 is a composite view of FIGS. 19 and 20 with hidden lines shownfor clarity.

FIG. 22 is a section view along line I—I of FIG. 21.

FIG. 23 is a section view along line II—II of FIG. 21.

FIG. 24 is a top plan view of a fourth version of a first alternativeembodiment wherein solder or conductive epoxy connections using a pairof extra pieces electrically attach the PZT motors to the conductiveleads formed from the flexure material.

FIG. 25 is a bottom plan view of the version shown in FIG. 24.

FIG. 26 is a composite view of FIGS. 24 and 25 with hidden lines shownfor clarity.

FIG. 27 is a section view along line I—I of FIG. 26.

FIG. 28 is a section view along line II—II of FIG. 26.

FIG. 29 shows a bottom plan view of another embodiment.

FIG. 30 shows a top plan view of the embodiment of FIG. 29.

FIG. 31 is an enlarged fragmentary view of a portion of FIG. 30 showingdetails of the mounting arrangement for the PZT motors in thisembodiment.

FIG. 32 is a section view taken along line 8—8 of FIG. 31.

FIG. 33 is an exploded view of the suspension assembly of thisembodiment.

FIG. 34 is a perspective view of the suspension assembly of thisembodiment.

FIG. 35 is an exploded perspective view of the PZT motors, wire, andconductive trace layer showing details of the conductive pads forelectrically powering the PZT motors.

FIG. 36 is an enlarged plan view of a portion of the conductive tracelayer of FIG. 35 showing a layout for a wire bond pad used to connect toa first surface of the PZT motors and a plurality of trace pads used toconnect to a second surface of the PZT motors.

FIG. 37 is a top plan view of a first version of a second alternativeembodiment wherein the PZT motors are ultrasonically bonded toextensions of the conductive leads formed from the flexure material.

FIG. 38 is a bottom plan view of the version shown in FIG. 37.

FIG. 39 is a composite view of FIGS. 37 and 38 with hidden lines shownfor clarity.

FIG. 40 is a section view along line I—I of FIG. 39.

FIG. 41 is a section view along line II—II of FIG. 39.

FIG. 42 is a top plan view of a second version of the second alternativeembodiment wherein ultrasonic bonding using a separate piece toelectrically attach one side of the PZT motors to the conductive leadsformed from the flexure material.

FIG. 43 is a bottom plan view of the version shown in FIG. 42.

FIG. 44 is a plan view of the trace layer for the version shown in FIG.43.

FIG. 45 is a plan view of the substrate layer for the version shown inFIG. 43.

FIG. 46 is a plan view of the dielectric layer for the version shown inFIG. 43.

FIG. 47 is a composite view of FIGS. 42 and 43 with hidden lines shownfor clarity.

FIG. 48 is a section view along line I—I of FIG. 47.

FIG. 49 is a section view along line II—II of FIG. 47.

FIG. 50 is a plan view of the separate piece used in the version shownin FIG. 43.

FIG. 51 is an exploded view of the various layers of the separate pieceshown in FIG. 50.

FIG. 52 is a top plan view of a third version of the second alternativeembodiment wherein the PZT motors are attached using solder orconductive epoxy to extensions of the conductive leads formed from theflexure material.

FIG. 53 is a bottom plan view of the version shown in FIG. 52.

FIG. 54 is a composite view of FIGS. 52 and 53 with hidden lines shownfor clarity.

FIG. 55 is a section view along line I—I of FIG. 54.

FIG. 56 is a section view along line II—II of FIG. 54.

FIG. 57 is a top plan view of a fourth version of the second alternativeembodiment wherein solder or conductive epoxy connections using a pairof extra pieces electrically attach the PZT motors to the conductiveleads formed from the flexure material.

FIG. 58 is a bottom plan view of the version shown in FIG. 57.

FIG. 59 is a composite view of FIGS. 57 and 58 with hidden lines shownfor clarity.

FIG. 60 is a section view along line I—I of FIG. 59.

FIG. 61 is a section view along line II—II of FIG. 59.

FIG. 62 shows an exploded and composite view of the separate piece shownin FIG. 58.

FIG. 63 shows a top plan view of a third embodiment.

FIG. 64 is bottom plan view of the embodiment of FIG. 63.

FIG. 65 is an enlarged fragmentary view of a portion of FIG. 63 showingdetails of the mounting arrangement for the PZT motors in thisembodiment.

FIG. 66 is a still further enlarged section view taken along line 12—12of FIG. 65.

FIG. 67 is an exploded perspective view of the suspension assembly ofFIG. 63.

FIG. 68 is a perspective view of the suspension assembly of FIG. 63.

FIG. 69 is a top plan view of a first version of a third alternativeembodiment wherein the PZT motors are ultrasonically bonded toextensions of the conductive leads formed from the flexure material.

FIG. 70 is a bottom plan view of the version shown in FIG. 69.

FIG. 71 is a composite view of FIGS. 69 and 70 with hidden lines shownfor clarity.

FIG. 72 is a section view along line I—I of FIG. 71.

FIG. 73 is a section view along line II—II of FIG. 71.

FIG. 74 is a top plan view of a second version of the third alternativeembodiment using ultrasonic bonding of a separate piece to electricallyattach one side of the PZT motors to the conductive leads formed fromthe flexure material.

FIG. 75 is a bottom plan view of the version shown in FIG. 74.

FIG. 76 is a composite view of FIGS. 74 and 75 with hidden lines shownfor clarity.

FIG. 77 is a section view along line I—I of FIG. 76.

FIG. 78 is an enlarged plan view of the separate piece useful in thepractice of the version shown in FIG. 74.

FIG. 79 is an exploded view of the layers making up the separate pieceof FIG. 77.

FIG. 80 is a section view along line II—II of FIG. 76.

FIG. 81 is a top plan view of a third version of the third alternativeembodiment wherein one side of the PZT motors is attached using solderor conductive epoxy to an extension of the conductive leads formed fromthe flexure material and the other side of the PZTs is bonded toconductive pads in the conductive trace layer of the flexure.

FIG. 82 is a bottom plan view of the version shown in FIG. 81.

FIG. 83 is a composite view of FIGS. 81 and 82 with hidden lines shownfor clarity.

FIG. 84 is a section view along line I—I of FIG. 83.

FIG. 85 is a section view along line II—II of FIG. 83.

FIG. 86 is a top plan view of a fourth version of the third alternativeembodiment wherein solder or epoxy connection is used with a separatepiece to electrically attach the PZT motors to the conductive leadsformed from the flexure material.

FIG. 87 is a bottom plan view of the version shown in FIG. 86.

FIG. 88 is a composite view of FIGS. 86 and 87 with hidden lines shownfor clarity.

FIG. 89 is a section view along line I—I of FIG. 88.

FIG. 90 is a section view along line II—II of FIG. 88.

FIG. 91 shows a top plan view of a fourth embodiment having aprefabricated motor subassembly.

FIG. 92 shows a bottom plan view of the embodiment of FIG. 91.

FIG. 93 is an enlarged fragmentary view of a portion of FIG. 91.

FIG. 94 is an enlarged section view taken along line 16—16 of FIG. 93.

FIG. 95 shows an exploded view of the prefabricated motor subassemblyand head suspension assembly of which it forms a part.

FIG. 96 shows a perspective assembly view of the embodiment of FIG. 95.

FIG. 97 is a top plan view of a first version of a fourth alternativeembodiment wherein the PZT motors in a prefabricated subassembly areultrasonically bonded to extensions of the conductive leads formed fromthe flexure material.

FIG. 98 is a bottom plan view of the version shown in FIG. 97.

FIG. 99 is a composite view of FIGS. 97 and 98 with hidden lines shownfor clarity.

FIG. 100 is an enlarged plan view of a motor subassembly metal substratefrom FIG. 97.

FIG. 101 is a plan view of a dielectric layer for the motor subassemblyof FIG. 97.

FIG. 102 is a plan view of a conductive pad layer for the motorsubassembly of FIG. 97.

FIG. 103 is a section view along line I—I of FIG. 99.

FIG. 104 is an enlarged plan view of a composite or wireform drawing(with hidden lines shown for clarity) of the metal substrate of FIG.100, together with the dielectric layer of FIG. 101 and the conductivepad layer of FIG. 102.

FIG. 105 is an enlarged plan view similar to that of FIG. 104, exceptshowing the lead extensions and a portion of the dielectric layer fromthe flexure.

FIG. 106 is a section view along line II—II of FIG. 99.

FIG. 107 is a top plan view of a second version of the fourthalternative embodiment wherein ultrasonic bonding using a pair of extrapieces electrically attach the PZT motors to the conductive leads formedfrom the flexure material.

FIG. 108 is a bottom plan view of the version shown in FIG. 107.

FIG. 109 is a composite view of FIGS. 107 and 108 with hidden linesshown for clarity.

FIG. 110 is an enlarged composite or wireform view (with hidden linesshown for clarity) of the motor subassembly of FIG. 108, together withthe separate pieces of laminate connecting the motor subassembly to aportion of the flexure.

FIG. 111 is a section view along line I—I of FIG. 109.

FIG. 112 is a section view along line II—II of FIG. 109.

FIG. 113 is a top plan view of a third version of the fourth alternativeembodiment wherein the PZT motors are attached using solder orconductive epoxy to extensions of the conductive leads formed from theflexure material.

FIG. 114 is a bottom plan view of the version shown in FIG. 112.

FIG. 115 is a composite view of FIGS. 113 and 114 with hidden linesshown for clarity.

FIG. 116 is an enlarged composite or wireform view (with hidden linesshown for clarity) of the motor subassembly of FIG. 113, together withlead extensions and solder connections between the motor subassembly anda portion of the flexure.

FIG. 117 is a section view along line I—I of FIG. 115.

FIG. 118 is a section view along line II—II of FIG. 115.

FIG. 119 is a top plan view of a fourth version of the fourthalternative embodiment wherein solder or conductive epoxy connectionsusing a pair of extra pieces electrically attach the PZT motors to theconductive leads formed from the flexure material.

FIG. 120 is a bottom plan view of the version shown in FIG. 119.

FIG. 121 is a composite view of FIGS. 119 and 120 with hidden linesshown for clarity.

FIG. 122 is an enlarged composite or wireform view (with hidden linesshown for clarity) of the motor subassembly of FIG. 119 together withseparate pieces of laminate using solder connections between the motorsubassembly and a portion of the flexure.

FIG. 123 is a section view along line I—I of FIG. 121.

FIG. 124 is a section view along line II—II of FIG. 121.

DETAILED DESCRIPTION

In the practice of the present invention, the PZT is electricallyisolated from what has heretofore been a grounding substrate. In thisarrangement, each major face of the PZT is independently available forreceiving a driving voltage, permitting the use of a unipolar voltagesource to obtain both expanding and contracting modes of operation ofthe PZT (i.e., when either major face may be connected to circuit commonor “ground”). Furthermore, this result is obtained while the primaryplane of the PZT is kept parallel to the primary plane of the stainlesssteel load beam of the head suspension. Maintaining this parallelismgreatly simplifies the attachment of the PZT to the substrate, and keepsa low profile for the overall assembly, in contrast to prior artarrangements where the PZT is not parallel to the primary plane of theload beam. It is to be understood that “unipolar voltage source” refersto a single polarity electrical voltage source wherein, for example, apositive voltage potential is applied to a first major surface of thePZT motor when measured with respect to a reference voltage potential ata second major surface of the PZT element (which is normally at a groundor “circuit common” potential). In order to obtain both the expandingand contracting modes of operation in the practice of the presentinvention, the second (normally the bottom) surface of each of the twoPZT motors must be isolated from any mechanical contact which wouldinherently “ground” those surfaces, since the unipolar source must bereconnected with reversed polarity to the PZTs to switch operation fromthe expanding mode to the contracting mode (or vice-versa). In contrastto a unipolar source, a bipolar source has the ability to change thepolarity of the voltage supplied on its output terminal, when measuredwith respect to circuit common. However, bipolar sources are typicallymore complicated and hence more costly than unipolar sources (even withoutput switching of both terminals for a unipolar source) and thus thereis a need for PZT loads to be able to be driven from unipolar sources. Ahead suspension typically includes a load beam, in which case the loadbeam forms a species of substrate for the present invention, which maybe suitable for assemblies other than head suspensions. It is further tobe understood that the metal layer forming the load beam for a headsuspension may have additional portions forming a spring region and amounting region for receiving a mounting plate.

One embodiment of this invention may be seen in FIGS. 1–5 and is a diskdrive head suspension or assembly 20 which allows electrical isolationof the PZT from the ground or circuit common connection, whilepermitting wire bonding to the PZT at both major surfaces (top andbottom) of the PZT. Head suspension 20 includes a pair of PZT motors 22,24. As used herein it is to be understood that the terms “top” and“bottom” are relative terms, in that typically disk drive headsuspensions are employed on both sides of a disk. As such, “top” refersto the free side or major surface 26 of the PZT 22 or 24 facing awayfrom the suspension 20 which is visible in FIG. 1, and “bottom” refersto the major surface 28 of the PZT facing towards the suspension 20,partially visible in FIG. 2, FIG. 4 shows an enlarged plan view detailof a portion of the assembly 20 from the same side as shown in FIG. 2.In an exploded view, FIG. 6 shows the PZT motors 22 and 24, a firstconnection means 32 in the form of a top wire stitch 32 a, a secondconnection means 34 in the form of a bottom wire stitch 34 a, astainless steel substrate 30 (here in the form of a load beam 30 a, astainless steel layer 38 for a flexure 40, a dielectric layer 42, and alayer of conductive traces 44 preferably formed of copper. The flexure40 is made up of the stainless steel layer 38 for the flexure, thedielectric layer 42 and the copper traces 44. The connection means 32,34 (shown in this embodiment in the form of wire stitches 32 a, 34 a)are for making electrical connections between the PZT motors 22, 24 andthe conductive traces 44. A first aperture 46 in the load beam orsubstrate 30 enables the top wire stitch 32 a (or first connection means32) to be attached to a first bonding pad 56 electrically connected toone of the copper traces 44. In FIG. 6 the suspension 20 includes amounting plate 50, and the substrate 30 has a second aperture 52 and athird aperture 54 for connection to the bottom conductive surfaces ofthe PZTs 22 and 24. Conductive copper traces 44 have a first bonding pad56 and a second bonding pad 58. It is to be understood that the topsurfaces 26 of each of the PZT motors 22 and 24 is conductive.

It is to be understood that in the version shown in FIGS. 1–8, the PZTmotors 22 and 24 are electrically insulated from the stainless steelsubstrate/loadbeam 30 by an insulating epoxy 60 shown somewhatschematically in FIG. 6. In this embodiment, each PZT motor ismechanically, but not electrically, bonded via a bottom conductivesurface 28 (i.e., the second major surface) to the substrate 30 (e.g.,load beam 30 a), typically made of stainless steel, using an adhesive(such as epoxy) that is filled with beads made of an insulatingmaterial. The adhesive is a type RP 672-1A (Alumina filler) or RP 672-1S(Silica filler) available from Ablestik at 20021 Susana Rd., RanchoDominguez, Calif. 90221. The average particle size for the aluminafiller is about 1 micron up to a maximum particle size of about no morethan 5 microns. No surface treatment is required for the alumina fillerversion of the adhesive. For the silica filler version, the surface ispreferably treated with a silane adhesion promoter, and the averageparticle size is about 4.5 microns, with a maximum particle size ofabout no more than 15.5 microns. For both the silica and alumina fillertype adhesives, spacers are preferably glass beads with a particle sizerange of about 9 to about 20 microns in diameter.

It is to be understood that the adhesive (insulating epoxy) extends oversome, but not all, of the bottom surface, and electrically isolates themechanically bonded conductive surface 28 of the PZT 22 or 24 from theground plane of the suspension 20 formed when the substrate 30 isconductive. A pair of openings, (the second and third apertures 52, 54)in the substrate 30 aligned with the region free of adhesive permitelectrical connection to the bottom conductive surface 28 of each PZT.Electrical connection to the top conductive surface 26 (i.e., the firstmajor surface, on the non-disk side in this arrangement) of each PZT iscompleted (in this embodiment) using a standard ultrasonically bondedtop wire stitch 32 a, the structure and method of which have beenutilized on prior art designs and are conventional. The electricalconnection to the bottom conductive layer of the PZT is also completedwith an ultrasonically bonded bottom wire stitch 34 a, but is completedfrom the disk side of the suspension through access features (such asthe second and third apertures 52 and 54 in the load beam 30 a) in aregion where the adhesive is absent. It is to be understood that the twoPZT motors 22 and 24 have opposite polarizations with respect to eachother such that when the same voltage is applied to the PZT motors usingthe parallel electrical connection shown, one PZT will contract and theother PZT will expand in the direction parallel to the major surfaces ofthe PZT motors, thus “steering” the distal end 62 of the head suspension20 laterally in a first direction 64. It is to be further understoodthat by applying an oppositely poled voltage across the pair ofelectrically parallel connected PZTs, the distal end of the headsuspension will be driven in a second direction 66 diametricallyopposite the first direction 64, as shown in FIG. 4 b.

Referring now most particularly to FIGS. 4 and 6, the second and thirdapertures 52 and 54 in the stainless steel load beam 30 a are eachaligned with one of the PZTs 22, 24 to permit electrical connectionthereto. In this embodiment, the first aperture 46 (together with amirror image aperture 48) also serves the purpose of providing a “hinge”to permit lateral movement of the distal end 62 of the load beam 30 awhen driven by the expansion and contraction of the PZT motors 22 and24. FIGS. 7 and 8 show perspective views of the assembled version of theabove described embodiment.

It is to be understood that the present invention is also applicable toan assembly having only one PZT motor. Furthermore, it is within thepresent invention to use ultrasonic bonding of conductive leads formedfrom the flexure material as shown in FIGS. 9–13 or formed from anadditional add-on component as shown in FIGS. 14–18, similar instructure to the flexure to make the electrical connection to the PZTmotor(s). Additionally, it is within the present invention to useconductive epoxy or solder as shown in FIGS. 19–23 to attach conductiveleads formed from the flexure material or from an additional add-oncomponent similar in structure to the flexure as shown in FIGS. 24–28 tomake the electrical connection to the PZT motor(s).

Referring now most particularly to FIGS. 9 through 13, the version usingultrasonic bonding between the PZT motors 22, 24 and extensions of theconductive leads 44 formed from the flexure 40 may be seen. It is to beunderstood that FIG. 11 is a “composite” or wireform view of the detailsof FIGS. 9 and 10 as if the parts of the assembly 20 were transparent.In this version, leads 44 from the flexure 40 are extended as shown at44 a to overlap the PZT motors 22, 24 on the free side 26 and at 44 b tooverlap the opposite side 28 of the PZT motors 22, 24. Conventionalultrasonic bonding is used to mechanically and electrically secure therespective overlapping portions 44 a and 44 b of the leads 44 where theycontact the PZTs 22, 24 to form electrical connections between the leads44 and the PZTs 22, 24 in a manner analogous to the wire stitch versiondescribed above. The stainless steel layer 38 supports a portion of therespective lead extensions 44 a and 44 b, and the dielectric layer 42insulates lead extension 44 b from the substrate 30 or load beam 30 a aslead extension passes over the region intermediate the second and thirdapertures 52 and 54, as shown in FIG. 13. The stainless steel layer 38supports lead extension 44 a (insulated by dielectric layer 42) as itpasses through the first aperture 46, as shown in FIG. 12. The leadextension 44 a is formed into an offset or “Z-shaped” configuration toposition lead extension 44 a in the plane of surface 26, as it extendsfrom the main body portion of flexure 40, which in this embodiment, ismounted via stainless steel layer 38 on the opposite side of the loadbeam 30 a.

Referring now to FIGS. 14 through 18, a further version of the presentinvention may be seen. In this version, ultrasonic bonding is used witha pair of intermediate pieces formed from a three layer laminate similarto the flexure 40. Again it is to be understood that FIG. 16 is awireform view or composite of FIGS. 14 and 15. In this version, a pairof separate pieces 70, 72 connect the leads 44 with the PZT motors 22,24. A conductor 74 in piece 70 connects to the free side 26 of the PZTs22, 24. Similarly, a conductor 76 in piece 72 connects to the other side28 of PZTs 22, 24. Conductors 74 and 76, formed, respectively asconductive traces 44 c and 44 d in the laminated pieces 70, 72 areconnected, respectively, to individual leads from among the group ofleads 44 in flexure 40 for powering the PZTs. An electrical connectionis made through first aperture 46 to connect leads 44 to piece 70, andthe conductor 76 extends through the second and third apertures 52 and54 to provide electrical connection to side 28 of the PZTs. Ultrasonicbonding is used to form the connections mentioned with respect to thisversion.

Referring now to FIGS. 19 through 23, a version similar to that of FIGS.9 through 13 may be seen. In this version, solder or conductive epoxyconnections 80 replace the ultrasonic bonding of conductors 44 of leadextensions 44 a and 44 b to the PZTs 22, 24.

Referring now to FIGS. 24 through 28, a version similar to that of FIGS.14 through 18 may be seen. In this version, solder connections 80 areused with separate pieces 70, 72 to electrically and mechanically bondconductors 44 c and 44 d to the PZTs 22, 24. The separate pieces 70 and72 may be formed of a laminate of a trace layer, an insulating layer,and a support layer, similar or identical to the laminate of the flexure40 described above.

There are also other embodiments of the innovation which allowdifferential actuation as follows. Referring now most particularly toFIGS. 29–36, a second wire stitch type embodiment of the presentinvention may be seen. In this embodiment, the PZT motors 22, 24 aremounted on the disk side of the suspension 20 a. FIGS. 29 and 30 showbottom and top plan views of this embodiment, and FIG. 31 is an enlargedfragmentary view of a portion of FIG. 30 showing details of the mountingarrangement and a wire or wire bond 82 and wire bond pad 84 for the PZTmotors 22, 24 in this embodiment. FIG. 32 is a section view taken alongline 8—8 of FIG. 31. FIG. 33 is an exploded view of the suspensionassembly of this embodiment. FIG. 34 is a perspective view of thesuspension assembly 20 a of this embodiment. FIG. 35 is an explodedperspective view of the PZT motors, wire bond pad 84 for the top wirestitch connection 82, and conductive trace layer 44 e showing details ofthe conductive epoxy pads 86 and trace pads 88 for mechanically bondingand electrically connecting to the PZT motors 22, 24.

In this embodiment, the PZT motors are mechanically and electricallybonded to trace pads 88 (or conductive pads), preferably made of goldplated copper on a flexure on the disk side of the suspension. Theflexure 40 a is made up of a stainless steel substrate 38 a, adielectric layer 42 a (preferably of polyimide), and a conductive tracelayer 43 containing conductive traces 44 e (preferably of copper). Themechanical and electrical bonding is accomplished simultaneously using aconventional conductive epoxy adhesive to electrically connect one side(the bottom) of the PZT to the trace pads 88. In this embodiment, allfour trace pads are at the same electrical potential. The remaining(top) electrical connection to the PZT is completed using the wire bondpad 84 in the conductive trace layer 43 electrically connected to anultrasonically bonded gold wire (top wire stitch connection or “wirebond”) on the disk side of the suspension. It is to be understood thateach PZT is otherwise electrically isolated from the stainless steelsubstrate (and load beam) by the dielectric layer 42 a, as may be seenin FIG. 33. More particularly, dielectric layer 42 a has insulating pads90 interposed between copper pads 88 and areas 92 of the stainless steelflexure substrate 38 a. FIG. 36 illustrates the electrical layout of thewire bond pad 84 and trace pads 88 and connections 94 to individualtraces in the conductive trace layer 43.

It is to be understood to be within the scope of the present inventionto provide an assembly having only one PZT motor. Furthermore, it iswithin the present invention to use ultrasonic bonding of conductiveleads formed from the flexure material as shown in FIGS. 37–41 or to useultrasonic bonding of conductive leads formed from an additional add-oncomponent as shown in FIGS. 42–49 to make the electrical connection tothe PZT motor. Additionally, it is within the present invention to useconductive epoxy or solder as shown in FIGS. 52–56 to attach conductiveleads formed from the flexure material or from an additional add-oncomponent shown in FIGS. 57–61 to make the electrical connection to thePZT motor. The versions shown in FIGS. 37 through 61 each have the PZTmotors 22, 24 mounted on the disk side of the suspension, as were shownin FIGS. 29–36.

In the version shown in FIGS. 37–41, electrical connection is made tothe surface 28 of the PZTs 22 and 24 in a manner similar to that shownin the previous version using trace pads 88 insulated from the stainlesssteel layer 38 b by insulating pads 90 a, except that ultrasonic bondingis used, as was done with respect to the version shown in FIGS. 9–13. Alead extension 96 is used to make electrical connection to the free side26 of the PZTs 22 and 24, again using ultrasonic bonding. As may be seenmost clearly in FIG. 41, the lead extension 96 has its laminate“inverted” by being folded over, such that the conductive trace 98 isfacing and abutting side 26 of the PZTs, while being insulated by layer99 and supported by the stainless steel layer 100.

Referring now most particularly to FIGS. 42–49, another version of thepresent invention may be seen in which one separate piece is used toconnect the leads in the flexure to the free side 26 of the PZTs. Inthis version, a separate piece 102 is formed of the same laminate as theflexure material may be used to connect leads 44 to the PZTs 22 and 24.FIGS. 44 45, and 46 show a trace layer 104, a dielectric layer 106, anda stainless steel layer 108 useful in the practice of this version.FIGS. 50 and 51 show, respectively, the separate piece 102 in plan view,and the various layers in a separated or exploded view. Layer 110 is aconductive trace layer, layer 112 is a dielectric layer, and layer 114is a substrate which may be formed of stainless steel.

Referring now to FIGS. 52 through 56, a version of the present inventionmay be seen in which the PZT motors are electrically and mechanicallyconnected to extensions of the conductive traces by solder connections116. In this version, the free side 26 of the PZTs 22 and 24 isconnected to an extension 118, and the other side 28 of the PZTs isconnected to trace pads 120 forming part of a trace extension 122similar to that shown in FIG. 44.

In FIGS. 57 through 61, a version using solder connections 116 with aseparate piece 124 to connect to side 26 of the PZTs may be seen. FIG.62 shows the various layers of the separate piece 124, and also shows aplan view of the laminated separate piece 124. Piece 124 includes aconductor layer 126 (which may be formed of copper or a copper alloy), adielectric layer 128 (which may be formed of polyimide), and a substratelayer 130, (which may be formed of stainless steel). The trace pads andextension shown in FIG. 44 (or a similar arrangement) may be used toconnect to side 28 of the PZT motors 22 and 24.

Referring now to FIGS. 63–68, a third wire stitch alternative embodimentof the present invention with PZT motors 22, 24 mounted on the non-diskside of the suspension 20 b may be seen. FIGS. 63 and 64 show the topand bottom plan views of this embodiment, and FIG. 65 is an enlargedfragmentary view of a portion of FIG. 63 showing details of the mountingarrangement for the PZT motors 22, 24 in this embodiment, but withoutshowing the wire bond 82. FIG. 66 is a still further enlarged sectionview taken along line 12—12 of FIG. 65. FIG. 67 is an explodedperspective view of the suspension assembly 20 b of FIG. 63, showing thePZT motors 22,24, the wire connection 82, the load beam 30 c withapertures 132, a flexure metal substrate 134 with apertures 136, adielectric layer 138 with apertures 140, a plurality of controlledamounts 142 of conductive epoxy, a conductive trace and pad layer 144having a plurality of conductive pads 146 and a wire bond pad 148, and amounting plate 50. As may be seen most clearly with respect to FIG. 67,the surface 28 of each of the PZT motors 22, 24 is mechanically mountedon the conductive pads 146 in the conductive trace layer 144 using adiscrete amount of conductive epoxy 142, thus also providing anelectrical connection to the surface 28 of the PZT motors 22 and 24. Themechanical and electrical connection is enabled by the apertures 132,136, 140 aligned with the PZT motors in each of the load beam 30 c,flexure metal substrate 134, and dielectric layer 138. The wire bond 82makes an electrical connection between the wire bond pad 148 in theconductive layer 144 and the surface 26 of the PZT motors 22 and 24.FIG. 68 is a perspective view of the suspension assembly 20 b of thisembodiment. As may be most clearly seen in FIG. 66, the mechanicalconnection between the PZT motors and the load beam is via therespective overlaps between the conductive pads 146, the dielectriclayer 138 and the metal substrate 134 of the flexure, it beingunderstood that in this embodiment the flexure 40 is made up of at leastthe flexure metal substrate 134, the dielectric (insulating) layer 138and the conductive trace layer 144. It may thus be seen that the forcedeveloped by the PZT's is transferred first via conductive epoxy 142 tothe conductive pads 146, and then through the dielectric layer 138 tothe flexure metal substrate 134. The force is then transferred from themetal substrate 134 to the load beam 30 c via a plurality of 6 laserwelds, indicated by the asterisks (“*”) 150 in FIG. 64.

This embodiment is similar to the previous (second) wire stitchembodiment with the PZT motors 22, 24 bonded to pads 146 (which may begold plated copper) on the flexure 40 except on the non-disk side of thesuspension. The PZT motors 22 and 24 are each placed throughappropriately sized apertures 132, 136 and 140 in the load beam and theflexure substrate and dielectric layers before being bonded to the pads146 of the conductive trace layer 144. The bonding is accomplished usinga conventional conductive adhesive 142. As has been described, theremaining electrical connection to the PZT is completed using anultrasonically bonded wire 82 (which may be gold) on the non-disk sideof the suspension. As may be seen most clearly in FIGS. 66 and 68, thisconcept also has the benefit of bringing the motors more “in-plane” withthe structure (i.e., into closer alignment with the primary plane 83 ofthe overall suspension assembly) to minimize gram share (the amount ofgram load carried by each individual PZT).

It is to be understood to be within the scope of the present inventionto provide an assembly having only one PZT motor. Furthermore, it iswithin the present invention to use ultrasonic bonding of conductiveleads formed as extensions from the flexure material as shown in FIGS.69–73 or to use ultrasonic bonding of conductive leads formed from anadditional add-on component as shown in FIGS. 74–80 to make theelectrical connection to the PZT motor. Additionally, it is within thepresent invention to use conductive epoxy or solder as shown in FIGS.81–85 to attach conductive leads formed from the flexure material orfrom an additional add-on component shown in FIGS. 86–90 to make theelectrical connection to the PZT motor.

Referring now most particularly to FIGS. 69 through 73, a versionsimilar to the third wire stitch version of the present invention may beseen in which a lead extension 152 replaces the wire bond or stitch 82.Lead extension 152 is a part of the flexure 40 and the conductive trace154 in extension 152 is ultrasonically bonded to the PZTs 22, 24.

Referring now to FIGS. 74–80, another version in which ultrasonicbonding is used with a separate piece of material 156 to from theconnection to surface 26 of the PZTs 22 and 24. The separate piece 156is formed of a laminate of a conductive layer 158, a dielectric layer160, and a stainless steel substrate layer 162.

In FIGS. 81 through 85, a version using solder to connect the PZTs witha lead extension 164 may be seen. Lead extension 164 is formed of thethree layer laminate of flexure 40, including a conductive layer 166, adielectric layer 168, and a supporting substrate 170 of stainless steel.

Referring now to FIGS. 86 through 90, a version similar to that of FIGS.74–80 may be seen in which a separate piece 172 is used similar to 156,except that there are enlarged circular pads 174 in the conductive layer158 to allow attachment using solder or conductive epoxy.

Referring now to FIGS. 91–96, a fourth alternative embodiment of thewire stitch version of the present invention may be seen. Thisembodiment has a prefabricated PZT motor subassembly 180 mounted on andforming part of the head suspension assembly. FIGS. 91 and 92 show thetop and bottom plan views of this embodiment, and FIG. 93 is an enlargedfragmentary view of a portion of FIG. 91 showing details of the mountingarrangement for the PZT motors 22, 24 in this embodiment, exceptomitting the wire bonds. FIG. 94 is an enlarged section view taken alongline 16—16 of FIG. 95 and showing the wire bond to the PZTs. In thisembodiment the pre-fabricated motor subassembly has PZT motors 22 and 24already attached to conductive pads 182 similar to pads 146 and whichare connected to a separate termination pad 184 on the motor subassembly180. The PZT motor subassembly 180 includes the PZT elements 22 and 24,a motor conductive pad layer 186 with the motor termination pad 184connected to the conductive pads 182 (for connection to the bottomsurface 28 of the PZT elements 22, 24), a motor insulator layer 188, anda motor metal substrate layer 190. The motor subassembly 180 ispreferably assembled first, and then installed (preferably by weldattachment at weld points 192 [indicated by the asterisks “*” in FIG.92] to the load beam 30 d of the suspension). Alternatively, the motorsubassembly 180 may be attached to the load beam 30 d by adhesive. Afterthe motor subassembly is mechanically or structurally attached to thesuspension, a first ultrasonic wire bond 194 is completed from the firstwire bond pad 196 in the conductive trace layer 198 of the suspensionflexure 200 to the motor subassembly termination pad 184, and a secondultrasonic wire bond 202 is completed from the second wire bond pad 204to the top surface 26 of both PZT motors 22 and 24 to complete theelectrical connections to the motor subassembly 180. FIGS. 95 and 96show, respectively, an exploded view and a perspective assembly view ofthe prefabricated motor subassembly and head suspension assembly towhich it is attached. This version has a flexure substrate 206, adielectric layer 208, and a conductive trace layer 210. Conductive epoxy212 is used to bond the surface 28 of the PZTs 22 and 24 to the motorconductive pads 182.

It is within the present invention to have a separate motor subassemblywhich uses ultrasonic bonding of conductive leads formed from theflexure material as shown in FIGS. 97–106 or to use ultrasonic bondingof conductive leads formed from an additional add-on component as shownin FIGS. 107–112 to make the electrical connection to the PZT motor.Additionally, it is within the present invention to use conductive epoxyor solder as shown in FIGS. 113–118 to attach conductive leads formedfrom the flexure material or from an additional add-on component shownin FIGS. 119–124 to make the electrical connection to the PZT motor in aseparate subassembly similar to subassembly 180 used with the wirestitch attachment described previously.

Referring now most particularly to FIGS. 97 through 106, a version ofthe present invention using a motor subassembly 220 may be seen. FIG.100 shows an enlarged plan view of a metal substrate layer 222 usefulfor the motor subassembly 220. FIG. 101 is a plan view of a dielectriclayer 224 for the motor subassembly 220, and FIG. 102 shows a conductivepad layer 226 for the motor subassembly 220. FIG. 104 shows the motorsubassembly 220 and FIG. 105 shows the motor subassembly with leadextensions 228 and 230, along with portions of the dielectric layer 232of the flexure to connect to the PZTs 22 and 24 in the motor subassembly220. In this embodiment, the lead extensions 228 is ultrasonicallybonded to the surface 26 of the PZTs 22, 24 and the lead extension 230is ultrasonically bonded to a bond pad 234 in the conductive pad layer226 which is mechanically and electrically bonded to surface 28 of thePZTs 22 and 24.

FIGS. 107–112 illustrate another variation of the present inventionwherein the motor subassembly 240 has a substrate 242, a dielectriclayer 244 and a conductive pad layer 246 connected to surface 28 of PZTs22 and 24. A first separate laminate piece 248 connects via ultrasonicbonding a first flexure bond pad 250 the surface 26 of PZTs, and asecond separate laminate piece 252 connects via ultrasonic bondingbetween a second flexure bond pad 254 and a conductive pad layer bondpad 256.

Similarly, referring now to FIGS. 113 through 118, lead extensions maybe used to provide solder or conductive epoxy connections to the motorsubassembly 260 in this version of the present invention. Motorsubassembly 260 has a substrate layer 262, a dielectric layer 264, and aconductive pad layer 266 which carries a conductive pad layer bond pad268. Solder or conductive epoxy connections at 270 and 272 connect afirst lead extension 274 from flexure 40 to the surface 26 of PZTs 22and 24, and solder or conductive epoxy connection 276 connects a secondlead extension 278 to the bond pad 268. The load beam 30 d for thisversion carries the motor subassembly and may make use of the assemblydetails described with respect to FIGS. 91–96.

Referring now to FIGS. 119 through 124, a version of the presentinvention may be seen in which two separate laminate pieces 280, 282 areused to connect to motor subassembly 260. In the view shown in FIG. 122,the PZTs have been omitted, along with the stainless steel layer 38 offlexure 40, and apertures 284 in the portion of dielectric layer 42 areshown for the first and second flexure bond pads 250 and 254 of theconductive layer 43 of the flexure 40. Solder connections 286 and 288may be used to connect separate pieces 280 and 282 as shown.

It is to be understood that in any of the above embodiments or versionsusing solder, that conductive epoxy may be used in place of the solder,while still remaining within the scope of the present invention.

Currently the chip set required to provide for both large positive andnegative voltages (on the order of +30 volts) with respect to circuitcommon to drive the PZT motors with a bipolar source cannot beincorporated into the other driver electronics. This increases the costof the hard drive by requiring that the drive circuit provide both +Vand −V outputs with respect to circuit common. The present inventionallows the hard drive controller to operate in a lower overall (althoughstill bipolar) voltage range while maintaining the same strokeperformance of the suspension, by dissociating the PZT's from circuitcommon so that either major surface of the PZT motors can be connectedto either the drive output or circuit common. With this invention, thedriver electronics can be incorporated into a single chip, decreasingcomponent costs at the hard drive level.

The present invention may thus be seen to be apparatus and method forselectively applying a voltage to one of a first and a second majorsurface of at least one of a pair of piezoelectric motors (PZTs) on adisk drive head suspension with a primary plane of a load beam of thehead suspension parallel to the major surfaces of the PZT elements,wherein the PZT elements are electrically insulated from the load beam.Electrical connection to the PZTs may be made via wires orelectro-mechanical attachment of a plated surface of the PZT with a bondpad on an electrically isolated substrate. The PZTs may be located on afirst or second major surface of the load beam, or may be assembled in apre-fabricated motor assembly before being installed in the headsuspension. Apertures in the load beam and other layers permit physicalinstallation of the PZT motors and enable electrical connection to aside of the PZTs that would otherwise be substantially inaccessible forsuch electrical connection.

This invention is not to be taken as limited to all of the detailsthereof as modifications and variations thereof may be made withoutdeparting from the spirit or scope of the invention. For example, andnot by way of limitation, the structure or technique shown or describedwith respect to one version or embodiment may be used with otherversions or embodiments where desired. By way of another example, andnot by way of limitation, the separate piece used in various embodimentsdescribed above may be an isolated conductor while still remainingwithin the spirit and scope of the present invention. Such an isolatedconductor may have an aspect ratio of width to thickness of about fiveto one or greater. Furthermore, such a separate piece may be formedgenerally in the z-axis direction (i.e., generally perpendicular to theplane of the suspension or the plane of one of the major surfaces 26 or28 of the PZTs) as desired to conform to the pad and PZT topography. Theisolated conductor may be attached via ultrasonic bonding, solder orconductive epoxy.

1. Apparatus for mechanically mounting and electrically connecting to apiezoelectric element on a head suspension comprising: a. anelectrically conductive substrate having a primary plane and forming apart of the head suspension; b. a piezoelectric element having a firstmajor surface that is generally planar and located parallel to theprimary plane; and c. an electrically insulating layer between thesubstrate and the piezoelectric element such that the piezoelectricelement is electrically insulated from all metallic structural parts ofthe head suspension; wherein the first major surface of thepiezoelectric element faces toward the substrate and wherein thesubstrate has an aperture aligned with a portion of the piezoelectricelement and the electrically insulating layer has a void aligned withthe aperture to provide access for electrical connection to the firstmajor surface of the piezoelectric element through the aperture andvoid.
 2. Apparatus for selectively applying a voltage to one of a firstand a second major surface of at least one of a pair of piezoelectricmotors on a disk drive head suspension with a primary plane of a loadbeam of the head suspension parallel to a major surface of thepiezoelectric motors, the apparatus comprising: a. a first electricalconnection to at least one of the piezoelectric motors on a first sidethereof; b. a second electrical connection to the at least onepiezoelectric motor on a second side thereof located opposite the firstside; wherein the at least one piezoelectric motor is electricallyinsulated from all metallic structural parts of the head suspension andat least one of the first and second electrical connections is madethrough an aperture in at least one structural part of the headsuspension.
 3. The apparatus of claim 2 wherein the other of the firstand second electrical connections to at least one of the piezoelectricmotors is an electro-mechanical attachment of a plated surface of the atleast one of the piezoelectric motors with a bond pad on an electricallyisolated substrate.
 4. The apparatus of claim 2 wherein the at least oneof the piezoelectric motors is located on one of a first and secondmajor surface of the head suspension.
 5. The apparatus of claim 2wherein the at least one of the piezoelectric motors is assembled in apre-fabricated motor assembly before being installed in the headsuspension.
 6. The apparatus of claim 2 wherein the at least oneaperture is formed in the head suspension in alignment with at least oneof the piezoelectric motors to enable electrical connection to a side ofthe at least one of the piezoelectric motors that would otherwise besubstantially inaccessible for such electrical connection.